ES2668654T3 - Stent graft - Google Patents

Abstract

Stent graft formed by a stent (1) with a plurality of annular segments (3) arranged side by side and joined together and with at least one marginal annular segment (4) with a meander-shaped web extension and at least one membrane (2), characterized in that in at least one marginal annular segment (4) with a meandering core extension, core loops (5) facing inward or outward are notched in such a way that they are formed elastic tabs (6) that are arranged by geometrical connection in the web loops (5) and that can move elastically against the web extension, the membrane (2) being clamped between elastic tabs (6) and web loops ( 5).

Description

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DESCRIPTION

Stent graft

The invention relates to a stent graft formed by a stent with a plurality of annular segments arranged next to each other and connected to each other and with at least one membrane. In addition, the invention relates to the use of such a stent graft for the treatment of vascular malformations.

Stent grafts of this type are implanted in blood vessels, for example to support abnormally enlarged or damaged or narrowed blood vessels. The combination of the stent and the membrane serves to treat more extensive vessel sections that require treatment and that require a longer length and especially also a greater flexibility of the implant. Stent grafts are especially used to bypass vascular malformations, for example to exclude aneurysms from the blood circulation. Balloon catheters are generally used for implantation of this type of stent grafts.

In the prior art it is known how to use stent grafts composed of two stents and a flexible membrane, for example Teflon, for this purpose. A stent graft of this type is described in EP2151217A1. The stent graft is composed of an inner stent and an outer stent coaxially arranged around the former, between which an expandable flexible membrane is arranged. The terminal areas of the stents with the membrane arranged between them are joined by welding.

WO01 / 66035A2 describes a stent graft formed by a stent with a plurality of annular segments arranged next to each other and connected to each other and at least one membrane, in which a joining core is arranged on the membrane of an annular segment and extends from this annular segment to the adjacent annular segment.

EP1266635A2 describes a stent graft having a cylindrical stent and a cylindrical membrane that are joined together for example through seams or hooks. Additionally or alternatively, the joint can be secured by a slight overlap of the stent and the membrane.

WO2009 / 035679A1 describes a stent graft having a continuous inner lining of polyester or ePTFE. In a zone of said inner lining a stent is disposed that wraps the inner liner coaxially. The areas of the inner lining next to the stent are lined with a second layer of polyester or ePTFE to increase the wall thickness of the implant in the area not protected by the stent. The terminal areas of the stent and the second layer slide towards each other. If necessary, a reinforcing material, for example ePTFE, can be applied additionally to the outer side of the stent graft components, especially in the transitions between the stent and the second layer.

Among stent grafts with a junction between the membrane and a stent, only that presented in EP1266635A2 exactly links a stent to exactly one membrane. The other solutions in the state of the art always require an additional stent or an additional membrane which for reinforcement are arranged coaxially around the first stent or the first membrane.

The solution according to EP1266635A2 uses hooks or threads for the connection between the stent and the membrane and / or alternatively an overlap of the two components. The durability of the hooks and threads that are exposed to great frictional forces within the blood vessel is always problematic. Similarly, there is a danger of tissue irritation or injury from protruding hooks or protruding edges between the stent and the membrane.

Therefore, the present invention aims to provide a stent graft that joins the stent and the membrane between them in a simple and durable manner, occupying less vascular lumen and causing no tissue irritation or injury.

This objective is achieved by the invention with stent grafting of the type mentioned at the beginning, with at least one marginal annular segment with a soul extension in the form of meanders in which soul loops oriented inward or outwardly are fitted in such a way. resulting in elastic tongues that are arranged by geometric union within the soul loops, being able to move elastically against the soul extension, the membrane being clamped between the elastic tongues and the soul.

The stent graft according to the invention is composed of a plurality of annular segments joined together which are arranged in the central area. These annular segments correspond to the annular segments of conventional stents as proposed and are being used in multiple ways. It is made and modified according to the invention at least one marginal annular segment that has an extension of the soul in the form of meanders and in whose soul loops elastic tabs are fitted.

By marginal annular segments are understood as annular segments that are arranged in the margin of the membrane. Generally, they are arranged either terminally on the stent, that is, by limiting the stent at its ends, or, they are arranged directly adjacent to the terminal annular segments. Preferably, they are terminal ring segments. According to the invention, only one of these segments

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Marginal annular may be provided with elastic tongues, but preferably they are marginal annular segments at both ends of the stent.

By extension of the soul in the form of meanders of the marginal annular segments, an extension of the soul in the form of waves is understood as an extension of the soul in the form of a zigzag. Soul and wave-shaped and zigzag-shaped extensions and annular segments are generally common in vascular stents to compensate at least in part for the contraction in length that occurs during expansion.

For the realization of the elastic tongues, the core loops of the marginal annular segments partially fit the core loops of the marginal annular segments, so that elastic tongues are formed that can move against the soul extension. They can be fitted or inwardly oriented soul loops or outwardly oriented soul loops, so that inwardly oriented elastic tabs or outwardly oriented elastic tabs are formed. In the state of fabrication of the stent (that is, before application by crimping onto a balloon or before expansion) the elastic tabs can be adapted by geometric bonding in the soul loops.

In order not to worsen the stability of the soul by the notches in the soul loops, it is convenient to increase, for example to double, the width of the soul in the area of the realization of the elastic tongues. This means that the elastic tongues have a substantially normal soul width.

The fixation of the membrane with the help of elastic tongues arranged next to each other in the stent allows an easy and safe union of the stent and the membrane. The elastic tongues arranged within the soul loops are produced, for example, by laser cutting. Tightening the membrane under the elastic tongues can be done with a simple manufacturing technique. Integration into the stent of the junction elements between the stent and the membrane as elastic tabs eliminates the danger that the junction components will be released from the stent and arrive freely mobile to the bloodstream, as can occur in other elements of Union.

In order to produce a homogeneous joint between the stent and the membrane, it is convenient to arrange a greater number of elastic tongues facing each other in the same direction. Especially, all the soul loops, oriented in the same direction, of the corresponding marginal annular segment are provided with an elastic tongue. These elastic tabs are then oriented parallel to the longitudinal axis of the stent and are preferably oriented towards the stent. The shape of the elastic tongues corresponds substantially to the shape of the soul loops.

Generally, the elastic tongues are oriented parallel to the longitudinal axis of the stent. But with a corresponding configuration of the notches and a corresponding contact of the marginal segments or soul loops, deviations from the parallelism are also possible.

The number of elastic tabs of a marginal annular segment basically depends on the desired stability of the respective joint between the stent and the membrane. Generally, at least two opposite soul loops of a marginal annular segment will be provided with elastic tongues, preferably all soul loops of the marginal annular segment.

The stent graft according to the invention will generally have a stent, made for example from a medically acceptable steel, expandable by a balloon catheter. Alternatively, variants are also possible in which the stent is self-expanding, for example, by using a shape memory alloy such as nitinol.

The membrane, generally a sheet or a flexible tube, can be composed of any usual material and admitted in medical technology. But PTFE and polyester are especially suitable. An ePTFE membrane is especially preferable. Additionally, the membrane may be functionally coated, for example with anti-inflammatory, anti-proliferative or therapeutic substances, for example, with rapamycin, paclitaxel or heparin. Preferably, the membrane is made in the form of a flexible tube and has the necessary elongation capacity to follow the stent expansion.

The marginal annular segment (s) with a soul extension in the form of meanders and the integrated elastic tongues are especially at the same time the terminal annular segments of the stent part of the stent graft according to the invention.

The elastic tabs of the marginal annular segments with a soul extension in the form of meanders are preferably oriented towards the stent. To improve the seat, the membrane clamped between the core loops and the elastic tongues can be retracted on itself in the terminal area that is located below the elastic tongues, to achieve a better tightening effect.

The stent graft according to the invention can have the membrane inside or outside. An arrangement of the membrane on the outer side is preferable. This arrangement has the advantage that the action of the stent structure on the vascular wall is attenuated by the intermediate membrane. Especially, the membrane is held by

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tighten at both ends of the stent in the marginal annular segments.

It is also possible a variant in which the membrane is fastened by tightening inside the stent on the elastic tongues, extending on the outside on the surface of the stent and being held at the opposite end in turn by the elastic tongues. In this case, the elastic tongues are preferably oriented outwards.

Preferably, the membrane is further immobilized by gluing in marginal annular segments. This can be done by means of an adhesive compatible with the body, but preferably through an adhesive tape that sticks on the membrane at the height of the elastic tongues. In addition to the aspect of the securing, such an adhesive tape also serves to protect the vascular wall against direct contact with the elastic tabs of the marginal annular segment.

The stent grafts according to the invention can have the membrane at any point and can also have more than one membrane. For example, the membrane may be arranged at one or the other end of the stent or centrally within the stent leaving free areas of the stent. In addition, it is possible to provide more than a single membrane which, for example, with its intermediate space that is free are arranged at the ends. If there is more than one membrane or so, each one by itself is immobilized in the stent structure through corresponding elastic tabs and, if necessary, by gluing.

If, for example, two membranes are arranged terminally, the part of the stent graft, not covered by a membrane, can be arranged in the area of a vessel bypass, so that blood flow to the derived vessel is not affected. For this purpose, the two stent halves that have the membrane can also be joined only loosely by so-called connectors. This also offers greater flexibility in this area.

Stent grafts according to the invention are first used for the treatment of vascular malformations. It can be the closure of derived vessels, but also the arrest of aneurysms or arteriovenous shunts.

In addition, embodiments are possible in which the stent graft according to the invention has two stent units that serve to hold an intermediate tubular membrane in a vessel. In this case, the stent has the tightening joint for immobilization of the membrane only at one end; The other end of the tubular membrane is attached to the second stent. A stent graft of this type can be implanted in damaged vessels of large area, for example after obliteration of the epithelial cell layer of a blood vessel.

Next, the invention is described in detail with the help of the figures. They show:

Figure 1 a modified stent according to the invention,

Figure 2 a stent graft according to the invention,

Figure 3 another stent according to the invention for fastening two membranes and

Figure 4 a stent according to the invention for the fastening of two membranes and a flexible connection of the two

stent pieces

Figure 1 shows a modified stent 1 according to the invention as modified for the immobilization of a membrane through elastic tongues 6. Stent 1 is composed of a plurality of annular segments 3 having a substantially zigzag-shaped extension. In the embodiment, stent 1 is represented in an open and extended state; in the original state after manufacture it is a tube composed of souls and provided with openwork, for example made of a medical or nitinol steel. Manufacturing is carried out in a manner known per se by laser cutting a tube of suitable dimensions.

The annular segments 3 are joined together by expansive elements 7, such that with a placement of the stent through a balloon, the length reduction resulting from the expansion of the annular segments 3 is compensated at least in part by a stretching of the connecting elements 7.

The marginal annular segment 4 at the end of the stent has an extension in the form of meanders. A zigzag-shaped extension would also be possible. The different souls form loops of soul 5 that extend in the form of waves or meanders through the circumference of the stent. The different soul loops 5 have, in the extension of their tabs oriented towards the notch stent 8 which result in the elastic tabs 6 that can move elastically against the general extension of the souls of the marginal annular segments 4. This allows insertion between the elastic tongues 6 and the soul loops 5 a membrane that is held there by tightening.

It should be mentioned that for a stent graft according to the invention the structure of the stent itself is not decisive. The annular segments can be structured in different ways. The important thing is that there is a marginal annular segment in which elastic tabs are fitted to immobilize a membrane in these.

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Figure 2 shows a stent graft according to the invention with a stent according to Figure 1 and with a membrane 2 inserted. You can see the two 5-terminal stent loops as well as the elastic tabs 6 that remain lying on the membrane 2. In case of securing the membrane on the stent with an adhesive means, for this purpose, an adhesive tape is glued on the elastic tabs 6 the membrane being placed.

Figure 3 shows a modified stent 1 according to the invention that is divided into two parts that can be covered individually by membranes respectively. On the left side, the marginal annular segments 4 are provided with core loops 5 and elastic tongues 6. Next, there are a series of annular segments that are joined together respectively through joining or expanding elements 7. In the central zone of the stent is another 4 '"marginal" annular segment with 5' core loops and 6 'elastic tongues. Below is a transition zone applied centrally on stent 1, with annular segments 3 'and expansion elements 7', following which are found another annular segment 4 '"marginal" with 5' core loops and elastic tabs 6 '. Then there are annular segments 3 that are joined through expansion elements 7 and (which is no longer represented) the other end of stent 1 with another marginal annular segment 4 with core loops 5 and elastic tongues 6.

The elastic tabs 6 and 6 'of the stent half shown on the left are oriented towards each other in the case represented and receive the tubular membrane from each other. The analog is valid for the right side of stent 1.

Figure 4 shows another embodiment of a stent according to the invention for the manufacture of a stent graft with two membranes. In this case, the stent 1 is also provided, at both ends, with marginal annular segments 4 (the left end is shown) which also have core loops 5 and elastic tongues 6. The elastic tongues 6 are oriented towards the stent . In addition, the stent has the usual annular segments 3 that cover the left part of the stent between the marginal segments 4 and 4 ', which in the finished stent graft is covered by the membrane. The individual annular segments 3 and 4 are connected to each other through joining elements 7.

Like the marginal annular segments 4, also the centrally arranged marginal 4 'annular segments have elastic tabs 6' and 5 'core loops.

The right half of the stent, represented only with the left end, corresponds at all points to the left half of the stent. The two halves of the stent are connected to each other by connectors 8. In the case represented, the stent 1 has a total of three connectors 8. The connectors leave in the two stent halves a greater free space, which allows on the one hand to leave Free outgoing vessels, but on the other hand, it also brings greater flexibility.

Apart from the connectors 8 or the annular segments 3 'and the connecting elements 7', the stent of Figure 4 corresponds in all other points to that of Figure 3.

A stent graft according to the invention is applied by crimping in the usual manner on a balloon catheter and is expanded with the usual technique at the place of use. During this, stent 1 is attached with membrane 2 to the vascular wall. The membrane 2 is located between stent 1 and the vascular wall.

Claims (13)

5 10 fifteen twenty 25 30 1. Stent graft formed by a stent (1) with a plurality of annular segments (3) arranged next to each other and joined together and with at least one marginal annular segment (4) with a soul-shaped extension meanders and at least one membrane (2), characterized in that in at least one marginal annular segment (4) with a soul extension in the form of meanders, soul loops (5) are oriented inward or outward, so that elastic tabs (6) are formed which are arranged by geometric union in the soul loops (5) and which can move elastically against the soul extension, the membrane (2) being held by tightening between elastic tabs (6) and loops of soul (5). 2. Stent graft according to claim 1, characterized in that at least one marginal annular segment (4) is arranged in a terminal manner. 3. Stent graft according to claims 1 or 2, characterized in that the elastic tabs (6) are oriented towards the stent. 4. Stent graft according to one of the preceding claims, characterized in that the stent (1) has a membrane (2) in the form of a flexible tube. 5. Stent graft according to claim 4, characterized in that the membrane (2) envelops the stent (1). 6. Stent graft according to one of the preceding claims, characterized in that the membrane (2) is secured within the elastic tongues (6) by gluing, preferably with adhesive tape. 7. Stent graft according to one of claims 1 to 6, characterized by several membranes (2) arranged in sections, which are respectively secured in elastic tongues (6). 8. Stent graft according to one of the preceding claims, characterized in that the marginal area of the membrane (2) clamped in the elastic tongues (6) is folded. 9. Stent graft according to one of the preceding claims, characterized in that the membrane (2) is composed of an ePTFE flexible tube. 10. Stent graft according to one of the preceding claims, characterized in that the stent (1) is a balloon expandable stent. 11. Stent graft according to claim 10, applied by crimping onto the balloon of a balloon catheter. 12. Stent graft according to one of claims 1 to 9, with a self-expanding stent of a shape memory alloy, especially nitinol. 13. Use of a stent graft according to one of claims 1 to 12 for the treatment of vascular malformations.